Wow! I have never seen a cutter disk /head/system quite like that.
In
theory it should work very well. The more cutters the less each has to do delivering more consistent power demand from the engine and a smoother cut.
I wonder if some of the problem may be how the cutter head is set up?
My conventional understanding is that ALL horizontal rotating cutter systems, should be set up to be slight lower at the front. The idea being that only the leading arc cuts, while the trailing is out of work (less drag).
My own experience would sagest that too often people assume the deck itself (a cowling) is the indicator of cutter head angle. This can lead to cutter head angle not being optimised for the job.
I would be checking the working angle of the cutter disk AND the engines working rpm before making any changes.
NOTE: Very few lawn mowers are designed / good for cutting long grass. Check out how an agricultural mower, designed for cutting tall/long material, for hay making or crop swathing, is designed - very diffrent.
